DE10008653A1 - Improvements in a radio communication system - Google Patents

Abstract

The disclosed invention is referred to a method for optimising the random access procedures in third generation CDMA cellular telephony systems. The particular embodiment of the example concerns a TD-SCDMA-TDD synchronous realization. The disclosed procedure includes a preliminary part charged to the network (BSSC, MSC) only for establishing the following associations between the configuration parameters of the involved physical channels: one signature burst (SYNC1) is associated to one forward access channel (P-FACH) only, in order to avoid any ambiguity in the mobile stations about where to look for the expected acknowledgement from the network; one random access common channel (P-RACH) is associated to one forward access channel (P-FACH) only, in order to reduce collision on the latter (P-RACH); one access grant channel (P/S-CCPCH, AGCH) only is associated to one random access common channel (P-RACH), in order to avoid any ambiguity in the mobile stations about where to look for the expected answer from the network with the indication of the dedicated service channels (DPCH); and each complete associative link binding the involved physical channels is included in the system information and broadcasted into the serving cell to be read by the mobile stations (MS, UE) when entering an actual part of the procedure charged to exchange protocol messages with the network (BSSC; MSC) through said associative links that being signalling at once to the mobile stations the route towards the services offered by the network, simplifying the access procedure consequently. Suitable groupings among: Downlink pilot sequences, Uplink pilot sequences, scrambling codes, basic midambles, are carried out in a cell-discriminating way and broadcasted into the cell to simplify the serving cell selection procedure.

Description

The cited documents [1] to [5] are called Considered the state of the art.

Relationship of the code sets used in TD-SCDMA

The following physical and logical channels are used in the TD-SDMA system:

• a) The physical DwPTS channel used in the Downward the cell-specific SYNC sequence (length 64 chip) through which the mobile stations pass the cell can identify in a network. This channel can also for the synchronization of base stations can be used with each other.
• b) The physical UpPTS channel, which carries in the upward direction the SYNC1 sequences (length 128 chip), which are transmitted by the mobile stations which try to access the system during the first access or handover.
  They are used to initially synchronize the mobile stations with the base stations in terms of timing and power. Different SYNC1 sequences distinguish different mobile stations that access.
• c) The physical P-FACH channel that brings the network response to a possibly recognized SYNC1 sequence. This message is delivered as a single burst so that it takes only one time frame.
  In response, the network of the recognized mobile station provides the proper timing and performance indicators to be used for the next send message.
• d) The physical P-RACH channel that the Channel request messages that are sent through the Mobile stations are sent to the Want to access system services. A mobile station sends such a message only after receiving the  Network confirmation (from the P-FACH) of a previously sent SYNC1 shock.
• e) The primary and / or secondary Central control channels (P-CCPCH or S-CCPCH) that the bring logical AGCH channel that the network response on a possible, correctly recognized and of course by the System includes accepted channel request message sent by a mobile station on the P-RACH becomes. This message will be the one from the incoming network Channels assigned to the mobile station included.

The problem to be solved is twofold:

• a) If more than one P-TRAY and more than one CCPCH, which bring the logical AGCH channel, per cell can be configured, as well as for the P-RACH, the accessing mobile station faces the problem opposite, knowing from which channel the Confirmation messages are expected and out which P-RACH to send the channel request message to is.
• b) Because the codes of the code sets are easily recognizable and must be signalable - especially with the initial cell search where the mobile stations do not know what codes in the base stations be used.

1. How has this problem been solved so far?

In the current CWTS specifications the 22 SYNC, 22 basic midamble and 22 Encryption keys with a unique relationship used. If a base station e.g. B. the first SYNC Has used the episode, then it also uses the first basic midamble code and also the first Encryption key.

There are 128 SYNC1 sequences in all base stations used.

2. How does your invention solve that specified technical problem (show advantages)?

The number and relationship of the different Code amounts are shown in the table below described:

Table 1

Relationship between the SYNC sequences, the SYNC1 sequences, the encryption codes and the midamble codes

SYNC episodes

There are 32 SYNC sequences. The advantage of the increased number is the reduced interference between adjacent ones. Base stations. With a hexagonal network structure, 19 different SYNC1 sequences in the form of two rings of cells around the cell in question (number 1) are required without the SYNC sequence being repeated in this cluster. See Figure 1.

Fig. 1 used by the cluster SYNC sequence

With only 22 SYNC sequences, one is not hexagonal network without neighboring cells with second order same SYNC sequence (which disturb each other) very much difficult to reach. 32 is also a good one Compromise for the detection of the SYNC sequences. The Efforts in the mobile station to identify the correct SYNC sequence increase with the number of SYNC Consequences.

SYNC1 episodes

Each SYNC sequence defines a group of x (8) SYNC1 sequences used for each base station become. Base stations with a different SYNC sequence have a different set of SYNC1 sequences (where Interference for different base stations certain SYNC1 sequences can be avoided).

Accordingly, there is also a good one Compromise between the maximum number of different, recognizable consequences on the one hand and the Capacity of direct access and handover on the other side. Thus there are a total of 256 in TD-SCDMA SYNC1 episodes available. The codes used and the The amount of code used is sent to the SYNC sequence connected and therefore neither have to be signaled nor be recognized.  

Encryption codes and midamble codes

Each SYNC sequence is also attached to a group of y (4) tied to basic midamble codes, and each of the basic midamble codes is on one unique encryption code attached. The The advantage is that once the SYNC sequence is known, only 4 basic midamble codes checked to find the right code and thus to be able to time slots this Recognizing cell together. In a cell they are basic midamble code and encryption codes the same for all carriers and time slots.

An additional advantage is that due to the additional increased number of codes and the possibility of performing one Encryption key jumping (midamble code jumping) in the set of 4 midamble codes (4 encryption codes) achieved further interference suppression can be.

The step according to the invention is as follows:

• a) determining a suitable composition of Code sets for using TD-SCDMA for Ensuring a good and future-proof Power.
• b) Linking the SYNC1 sequences, the basic ones Midamble codes and the encryption codes in Code groups to the SYNC sequences to avoid the Signaling and facilitating the recognition of the codes used in the respective cell.

Relationship of common physical and logical Channels in a TD-SCDMA system

The following physical and logical channels are used in the TD-SCDMA system:

• a) The physical DwPTS channel used in the Downward the cell-specific SYNC sequence (length 64 chip) leads. This sequence enables the Mobile stations, one cell in a network too identify, and can also be used for synchronization  base stations can be used with each other.
• b) The physical UpPTS channel used in the Upward the SYNC1 sequences (length 128 chip) leads that are sent by the mobile stations trying to access for a first time or during of the handover to access the system services.
• c) These episodes are used initially a mobile station on both the timing and also to the power level with the base station synchronize. Enable different SYNC1 sequences a distinction between different accessing Mobile stations.
• d) The physical P-FACH channel that the Network response to any correctly identified SYNC1 Consequence. This message is considered a single one Shock delivered so that it is only one frame long lasts.
• e) By the answer provided by P-FACH the network of the confirmed mobile station delivers the proper timing and performance level indicators for the next mobile station Send message must be used.
• f) The physical P-RACH channel that the Channel request messages that are sent through the Mobile stations are sent to the Want to access system service. A mobile station sends such a message only after it receives the Network confirmation (from the P-FACH) of a previously sent Received SYNC1 shock.
• g) The primary and / or secondary Central control channels (P-CCPCH or S-CCPCH) that the bring logical AGCH channel that the network response on any, correctly recognized and if by the System includes accepted channel request message by a mobile station on the P-RACH beforehand is sent.

This message is from the network of the inbound channels assigned to incoming mobile station.

The problems to be solved are the following:

• a) Since more than one P-FACH and more than one CCPCH can be configured per cell, just like for the P-RACH, the accessing mobile station faces the problem opposite, knowing what physical channel (i.e. from which P-FACH and CCPCH) they are on the relevant network response to a previously sent Message (SYNC1 or channel request) must wait.
• b) Since DwPTS and P-RACH share physical Channels are, they are collision events subject. A high probability of collision means a waste of spectrum resources (there collided messages must be sent again), and the disturbances in the system increase (that is, Capacity reduction). That is why the network should be means find to these events as much as possible limit.
• c) The SYNC1 sequences assigned to a cell are orthogonal sequences so that different SYNC1 bumps can be sent simultaneously and still in Recipients can be distinguished. That's why it can Network especially in heavily used environments possibly from the orthogonality property benefit to the number of confirmed at the same time Boost users by the configured P-TRAY be increased; however, here is the problem that to inform specific mobile stations from which P-FACH you should expect the relevant answers.
• d) In CDMA systems such as the TD- SCDMA is the minimization of the transmit power level in the system fundamental for optimizing the offered system capacity and quality; therefore would be the possibility of an incoming mobile station proper setting of their transmission power at Access to the P-RACH is very desirable. However, if there is more than one P-RACH in a cell the problem is knowing on which physical channel a mobile station uses Will send a channel request message.
• e) Due to the multicode transmission option  of CDMA systems it is possible that the time slot or the time slots of the radio frames on which a P- RACH has been configured, also brings traffic channels; this may be necessary in systems with high loads to improve the system capacity offered. In in this case the limitation of the collisions proves on this P-RACH as very beneficial for the quality the other users in the same location. However, this limitation still implies that the Network is able to access the incoming To control mobile stations on the P-RACH.

Before the invention described here, no solution to the above-mentioned problems was given in the following sense:

• - P-RACH was subject to collision events,
• - The mobile station had to configure all relevant channels (whereby P-FACH and CCPCH AGCH- Bring blocks) monitor to the expected Reply from the network to a previously sent Message SYNC1 or channel request) receive,
• - the network was not able to To inform FACH of the addressed mobile station, what performance setting to access the P-RACH and which P-RACH is to be used, about collisions on this physical channel to limit.

The network configures the P-FACHs; P-RACHs and the AGCH blocks per CCPCH according to its requirements, that is: according to the traffic it expects to have to supply by defining the following mappings:

• - Which SYNC1 sequences among those of this cell assigned to which P-FACHs are assigned: this assignment implies that any correctly recognized SYNC1 sequence from only one well-defined P-FACH or only well-defined P-FACHs through the network is confirmed. The requirement should be like this  read that a SYNC1 sequence is only one P-FACH is assigned to any ambiguity in the mobile station, where after the expected Avoid looking for a network response. Conversely, more SYNC1 sequences per P-FACH can be configured.
• - Which P-RACHs among which configured which P-FACHs are assigned: this implies that a mobile station that the network confirmation a previously sent SYNC1 sequence from a specific P-FACH receives their Channel request message only on one of the assigned P-RACHs. The Requirement should be a P-RACH only assign one P-FACH to avoid collisions the P-RACH that can occur if more P-FACHs of the same P-RACH correspond. Conversely, more P-RACHs per a P-FACH can be configured through this However, configuration becomes more difficult and imprecise, the mobile station the correct one Power level setting for access to to signal the assigned P-RACHS because the network does not know which of the Mobile station is selected. Note that according to the proposed method collisions can be limited on the P-RACH as a P-FACH only the confirmation of a SYNC1 impact can bring at once; this implies that this one mobile station only on the accesses assigned P-RACH at once, with Exception of possible false news detection from the radio interface.
• - Which P-RACHs among which configured which P / S CCPCHs that keep the AGCH blocks be assigned. This implies that a Mobile station that has a channel request message on a specific P-RACH has sent, only from the assigned primary  or secondary CCPCHs on the relevant Network response will wait for your request. Here the requirement should be that only one P / S-CCPCH assigned to one P-RACH can be to any ambiguity in the mobile station where after the expected Answer to look for from the net is too avoid.

The network sends (through the BCCH) in the Radio interface the implemented configurations, in order to inform the mobile stations that are on the Want to access system services.

The mobile station can then go through the following steps:

• - After reading the cell specific Configuration for the common physical channels (i.e. P-RACHs; P-FACHs; P / S-CCPCHs) the mobile station selects a SYNC1 Push that under the through the cell supported is selected and sends it on the physical UpPTS channel to the Cell;
• - The selection of the SYNC1 also corresponds to the Selection of a specific P-FACH; therefore monitors the mobile station after sending the selected SYNC1 impact the assigned P-FACH, to get the relevant answer from the network receive.
• - The selection of a SYNC1 impact corresponds also the selection of a specific P-RACH; after detection of the expected network response from a specific P-FACH to the the SYNC1 burst sent by the mobile station therefore their channel request message on the assigned P-RACH.
• - The selection of a SYNC1 impact corresponds also the selection of a specific P / S CCPCH; after sending the channel request The mobile station monitors the change message  therefore the assigned P / S-CCPCH to the get relevant answer from the network.

The relationship between the SYNC1 bumps and the affected common physical channels can be shown as follows:

SYNC1 → P-FACH → P-RACH → P / S-CCPCH

The steps according to the invention are provided by the following aspects:

• a) Finding a route between the affected common physical channels P-FACH, P-RACH and P / S-CCPCH, starting from the SYNC1 burst selected by the cell phone, to reduce collisions on the shared resources (ie P-RACH ) and to improve system capacity and quality; in particular:
  • - Linking the SYNC1 sequences to a specific P-FACH,
  • - Linking a specific P-RACH to a specific P-FACH
  • - Link to a specific P-RACH to a specific P / S-CCPCH that guides the AGCH blocks
• b) concatenating the above-mentioned routes so that the selection of a specific SYNC1 burst, which is carried out by the mobile station, determines all the other common channels involved for the access procedure. This chaining enables the following:
  • Simplification of detection in the mobile station, since it is always known from which common physical channel (P-FACH and P / S-CCPCH) the expected network responses are to be waited for,
  • - Optimization of access to shared channels (P-RACH), since the network knows in advance which physical channel the mobile station will choose for the next message sent (channel request)
  • Limit collisions on the shared channels (P-RACH) in favor of the incoming mobile stations as well as the other users who may be in the same location with this specific shared channel

Mapping BCH, PCH onto physical channels 1. Introduction

The present file describes the illustration from BCH and PCH to physical channels for TDD Low chip rate option.

2. Common transport channels

The following figure shows the image of the Transport channels for the option with low chip rate:

Fig. 1

Illustration of the transport channels

In the low chip rate option, the BCH (PCH) is mapped to the fixed position Td0 (see FIG. 2). Further details are given as follows:

1.1.1 The Broadcast Channel (BCH)

The BCH is based on at least one resource unit (RU) in the first downward time slot (Td0) shown per subframe. The BCH has one higher transmission power level (9-11 dB higher than that average power level in a RU) with a omnidirectional or sectorized patterns (without Beam shaping) to cover the entire cell area. The RU allocated for BCH would be shared with others shared control channels shared: PCH, according to a multi-frame structure.

1.1.2 The Call Channel (PCH)

The PCH is a special broadcast channel, with the UEs are called from the base station side, such as mentioned above it is also on the same downward Time slot 0 as BCH, followed by DwPTS (see the Literature [1]), shown, always with the same power level and the same antenna pattern how the BCH is broadcast. PCH and BCH take theirs own blocks in the multi-frame structure.

According to the frame structure, Td0 is replaced by DwPTS followed so that when the UE catches the SYNC word, it can easily win the BCH.

A. Conclusion

The low chip rate TDD option from 1.28 Mcps was already in the specification added. Based on the above Descriptions and to enable the low Chiprate with its specific properties proposed this new feature for the TDD option with low chip rate in clause 5.3.2.1 and 5.3.2.2 of TR25.928.

5.3.2 Common transport channels for the option with  low chip rate

The following figure shows the image of the Transport channels:

Fig. 1

Illustration of the transport channels

5.3.2.1 The Broadcast Channel (BCH)

The BCH is based on at least one Resource Unit (RU) in the first downlink Time slot (Td0) shown per subframe. Because of the use of intelligent antennas, the Time slot with BCH a higher transmit power level (9-11 dB higher than the middle one Power level in a RU) with omnidirectional or sectorized pattern (without beam shaping), in Comparison with the regular time slot, the is beamformed to cover the whole cell to provide. The RU allocated for BCH would be with other common control channels used: PCH, according to a multi-frame structure.  

5.3.2.2. The call channel (PCH)

The PCH is a special broadcast channel, with the UEs are called from the base station side, such as mentioned above, it is also on the same downward Time slot 0 as BCH, followed by DwPTS (see the Literature [1]) shown, always with the same power level and the same antenna pattern how it is sent by BCH. PCH and BCH take theirs own blocks in the multi-frame structure.

Direct access procedures for the TDD option with low chip rate introduction

The direct access procedures and the Collision problems are discussed in this document discussed.

Direct access procedures Prepare for direct access

When the UE is in standby mode down synchronization and reads the cell broadcast information. From the The UE receives the cell broadcast information Amount of code assigned to UpPTS SYNC1 for direct access is the number and position of the RACH channel that Number and position of the FACH channel, the operating mode (symmetrical or asymmetrical) of the cell and others Direct access information. Moreover the UE must control the timing and power level for the Send the direct access bursts according to the received one Estimate DwPTS from node B.

Direct access procedures

The SYNC1 sequence in UpPTS after the Security time slot is only used for upward Synchronization used; it is a well-known orthogonal gold code sequence. Send in this period  only the UEs (maximum 8 UEs) that the upward Want to sync with random selected gold code sequences with the estimated Time control and performance.

As soon as node B starts transmitting from a UE recognizes or has determined that the correlated Peak value can exceed the minimum threshold the time conceptions (TA) and the upward Power control (PC) can be achieved by using the detected arrival time and the power level of the SYNC1 with the expected arrival time and the expected Power levels are compared. Node B is responding to the UE by sending its control signaling over the selected FACH in the following subframe.

Once the UE has the control characters mentioned above received in the selected SUBJECT, his Access request accepted by node B. The UE then sets its time control and the Power level and sends the RACH in the Code channel that corresponds to the FACH. In this step the RACH sent to node B by the UE a high level of synchronization precision.

The UE and node B then switch Information and packages with access in the above-mentioned FACH / RACH pair and end the direct access procedure in the physical layer.

Random access collision

If a collision has occurred, or in an unfavorable propagation environment, the node can B SYNC1 not received. In these cases the UE receives no useful response from node B in the FACH of the next subframe, so the UE must transmit its Tx Time and Tx power levels based on the new Set SYNC and the SYNC1 after one Resend random delay.

In addition to the situations listed above, all types of UE procedures could be completed as follows:
If the UE has not recognized a response or an error response in the control signaling packets in the FACH, it abandons these packets. To avoid the risk of collision with other UEs, it retransmits the access request with the re-estimated Tx time and the re-estimated Tx power level based on a new SYNC after a random delay.

When the UE receives the down control signaling packets in which FACH received correctly, but the inband If the identification does not match, the UE gives it Packages on. To avoid the risk of collision it sends the access request with other UEs the re-estimated Tx time and the re-estimated Tx power level based on the new SYNC a random delay again.

When the UE receives the down control signaling packets in which FACH received correctly, but without in-band Identification, the UE abandons these packets. For Avoiding the risk of collision with other UEs it sets its Tx time and its Tx power level than the TA and PC information provided by node B Information and forwards the access request a random delay again.

If the access request in RACH is correct can be received by node B, and the Response from node B in FACH is also correct by the UE with matching inband If identification is received, the UE understands that the Node B has accepted its access request. The UE then sets its Tx time and its Tx Power level than that informed by node B. TA and PC information. And it sets its Access procedures in the same RACH / FACH pair of the next subframe.

If the UE on node B corresponds to the above  described method cannot gain access, it goes into the stand-by state.

Conclusion

This document describes the Direct access procedure of the option with lower Chiprate, it is suggested this new feature for the TDD option with low chip rate in the new one Clause 8.5 of TR 25.928.

Changes for 25,928 start 8.5 Direct access procedures 8.5.1 Preparation for direct access

When the UE is in standby mode down synchronization and reads the cell broadcast information. From the The UE receives the cell broadcast information Amount of code assigned to UpPTS SYNC1 for direct access is the number and position of the RACH channel that Number and position of the FACH channel, the operating mode (symmetrical or asymmetrical) of the cell and others Direct access information. Moreover the UE must control the timing and power level for sending direct access bursts according to the Estimate received DwPTS from node B.

8.5.2 Direct access procedures

The SYNC1 sequence in UpPTS after the Safety time slot is only used for upward synchronization station used; it is a well-known orthogonal Gold code sequence. Only the UEs transmit in this period (maximum 8 UEs) that the upward synchronization want to make, with randomly chosen gold code Follow with the estimated timing and Power.  

As soon as node B starts transmitting from a UE recognizes or has determined that the correlated Peak value could exceed the minimum threshold the time conceptions (TA) and the upward Power control (PC) can be achieved by using the detected arrival time and the power level of the SYNC1 with the expected arrival time and the expected Power levels are compared. Node 8 responds to the UE by sending its control signaling over the selected FACH in the following subframe.

Once the UE has the control characters mentioned above received in the selected SUBJECT, his Access request accepted by node B. The UE then sets its time control and the Power level and sends the RACH in the Code channel that corresponds to the FACH. In this step the RACH sent to node B by the UE a high level of synchronization precision.

The UE and node B then switch Information and packages with access in the above-mentioned FACH / RACH pair and end the direct access procedure in the physical layer.

8.5.3 Direct access collision

If a collision has occurred, or in an unfavorable propagation environment, the node can B SYNC1 not received. In these cases the UE receives no useful response from node B in the FACH of the next subframe, so the UE must transmit its Tx Time and Tx power levels based on the new Set SYNC and the SYNC1 after one Resend random delay.

In addition to the situations listed above, all types of UE procedures could be completed as follows:
If the UE has not recognized a response or an error response in the control signaling packets in the FACH, it abandons these packets. To avoid the risk of collision with other UEs, it retransmits the access request with the re-estimated Tx time and the re-estimated Tx power level based on a new SYNC after a random delay.

 When the UE receives the down control signaling packets in which FACH received correctly, but the inband If the identification does not match, the UE gives it Packages on. To avoid the risk of collision it sends the access request with other UEs the re-estimated Tx time and the re-estimated Tx power level based on the new SYNC a random delay again.

 When the UE receives the down control signaling packets in which FACH received correctly, but without in-band Identification, the UE abandons these packets. For Avoiding the risk of collision with other UEs it sets its Tx time and its Tx power level than the TA and PC information provided by node B Information and forwards the access request a random delay again.

 If the access request in RACH is correct can be received by node B, and the Response from node B in FACH is also correct by the UE with matching inband If identification is received, the UE understands that the Node B has accepted its access request. The UE then sets its Tx time and its Tx Power level than that informed by node 8 TA and PC information. And it sets its Access procedures in the same RACH / FACH pair of the next subframe.

If the UE is within the specified period Node B cannot gain access, it goes in Stand-by state over.

Changes from 25,928 end Mapping of EACH to physical channels introduction

The present file describes the illustration from RACH to physical channels for the TDD option with low chip rate.

Common transport channels

Fig. 1

Illustration of the transport channels

The figure shows the image of the Transport channels for the option with low chip rate:

The direct access channels (RACH)

The RACH is mapped to PRACH. With the high chip rate option, the PRACH can manage more than one slot per frame. The position of the slots allocated to PRACH is broadcast on the BCH. While in the low chip rate option discussed here (as shown in FIG. 1), the RACH channel is mapped to more than one (up to 8) RU in the first upward time slot (Tu0) per subframe. The same time slot can be used for RACH of more than one cell. Multiple transmissions using different codes could be received in parallel. The position assigned to RACH in the time slots is displayed on the BCH. The RACH uses both power control and up-sync control.

Conclusion

The low chip rate TDD option from 1.28 Mcps was already in the specification added. Based on the rules above and to enable the low chip rate with their specific properties is suggested this new feature for the low chip rate TDD option to be included in the new clause 5.3.2.4 of TR 25.928.

Changes from 25,928 start 5.3.2 Common transport channels 5.3.2.4 The direct access channels (RACH)

The RACH channel is for upward direct access designed by UE, it is based on more than one (up to 8) RU in the first upward time slot (Tu0) pro Subframe shown. The same time slot can be used for RACH can be used by more than one cell. Several Transmission using different codes could be received in parallel. The RACH in the Time slots allocated position is on the BCH displayed. The RACH uses both power control as well as up-sync control.

Changes from 25,928 end Upward synchronization for the TDD option with low chip rate introduction

Upward synchronization is one of those main features of the TDD option with lower Chip rate. It becomes a higher capacity and one Simplify the demodulator in node B.

The present work gives an introduction to the establishment and maintenance of the upward Synchronization.

Upward synchronization 1. The establishment of the upward synchronization 1.1 Preparation for upward synchronization (Downward synchronization)

When a UE is turned on, it searches the operating frequency band and tries several, strongest SYNC sequences in the down pilot time slot Find DwPTS from the nearby Bs nodes. To reading the cell broadcast information in BCH, the Following DwPTS, the UE maintains downward synchronization with DwPTS. This period is the making of the Downward synchronization. Only when the downward Synchronization is established, the UE can begin establish the upward synchronization.

1.2 Upward synchronization with open and closed loop

Although the UE is the downward Synchronization signal at this time from the Node B can receive is the distance to node B still indefinite, leading to unsynchronized Upward transmission can result. The transmission power and Clock concept for the first transmission of the UE are used according to the received Power level and the power level of node B set (open control loop). If the node B  recognizes the transmission of the UE in the search window, it evaluates the received power level and the Time control off. In the next down time slot Node B sends the setting information the UE for the modification of the timing and the Power level for the transmission and aligns the Upward synchronization procedure included (closed Control loop).

The procedure for making the upward Synchronization is usually done at the Access procedure used. It can also be used for Restoration of upward synchronization be used when synchronizing the Upward stretch was lost.

2. Maintain upward synchronization

Maintaining the upward Synchronization is in the proposed system important to be the midamble field in the frame structure in every traffic channel every major upward Time slot used.

In every major upward time slot is that Midamble different in each code channel. The BS can estimate the power level and the time shift, by putting the midamble field of each code channel in measures the same time slot. In the following downward The BS then sends the L1 control signaling time slot power control (PC) and timing (TA) through this mechanism and then enables that UE to set its Tx time correctly. This Procedures represent the reliability of the upward Synchronization sure. The upward synchronization can be checked once per TDD subframe. The Accuracy of upward synchronization remains in the Duration of 1/2 chip.

3. The estimate of the distance between node B and the UE

The up-synchronization requests the UE to send in advance a time shift (ΔT) which depends on the distance between the node B and the UE. Obviously one can estimate the distance between the node B and the UE using the known time shift:

d = C. ΔT (2)

where C is the speed of light.

It is obvious that the upward Synchronization reduces multiple access errors like and can increase the capacity (theoretically by 3 dB if multipaths could be negligible). And for other features that are lower in the system Chip rate can be used, such as intelligent antennas, the upward Provide synchronization a simple solution the details in another proposal by CWTS will be given.

Conclusion

The low chip rate TDD option from 1.28 Mcps was already in the specification added. Based on the above Descriptions and to enable the low Chiprate with its specific properties proposed this new feature for the TDD option with a low chip rate in the new clause 8.3.1 of the TR 25.928 record.

Changes from 25,928 start 8.3 Synchronization and cell search procedures 8.3.1 Upward synchronization 8.3.1.1 The establishment of the upward synchronization 8.3.1.1.1 Preparation for upward synchronization Downward synchronization

When a UE is turned on, it searches the operating frequency band and tries several, strongest SYNC sequences in the down pilot time slot Find DwPTS from the nearby Bs nodes. To reading the cell broadcast information in BCH, the Following DwPTS, the UE maintains downward synchronization with DwPTS. This period is the making of the Downward synchronization. Only when the downward Synchronization is established, the UE can begin establish the upward synchronization.

8.3.1.1.2 Upward synchronization with open and closed loop

Although the UE does the down synchronization signal received from node B at this time the distance to node B is still indefinite, which leads to unsynchronized upward Transmission can result. The transmission power and Clock concept for the first transmission of the UE are used according to the received Power level and the power level of node B set (open control loop). If the node B recognizes the transmission of the UE in the search window, it evaluates the received power level and the Time control off. In the next down time slot Node B sends the setting information the UE for the modification of the timing and the Power level for the transmission and aligns the Upward synchronization procedure included (closed Control loop).

The manufacturing procedure of the upward Synchronization, which is usually in the access procedure is used. You can also restore the Upward synchronization can be used when the Synchronization of the uplink was lost.

8.3.1.2 Maintaining upward synchronization

Maintaining upward synchronization  is important in the proposed system that Midamble field in the frame structure is in each Traffic channel of each main upward time slot ver turns.

In every major upward time slot is that Midamble different in each code channel. The BS can estimate the power level and the time shift, by putting the midamble field of each code channel in measures the same time slot. In the following downward The BS then sends the L1 control signaling time slot power control (PC) and timing (TA) through this mechanism and then enables that UE to set its Tx time correctly. This Procedures represent the reliability of the upward Synchronization sure. The upward synchronization can be checked once per TDD subframe. The Accuracy of upward synchronization remains in the Duration of 1/2 chip.

8.3.1.3. The estimate of the distance between the Node B and the UE

The up-synchronization requests the UE to send in advance a time shift (ΔT) which depends on the distance between the node B and the UE. Obviously one can estimate the distance between the node B and the UE using the known time shift:

d = C. ΔT (2)

where C is the speed of light.

Changes from 25,928 end Frame structure for the TDD option with lower Chip rate introduction

In 3GPP there are two options for the TDD  Mode. These are the high chip rate option (3.84 Mcps) and the option with low chip rate (1.28 Mcps). The current specifications for the TDD mode are mainly suitable for the option with high chip rate. Because of the difference in chip rate will be a new one in this proposal Frame structure for the TDD option with lower Chip rate suggested. To enable the low Chiprate with its specific characteristics and Properties will also later on through the CWTS other suggestions suggested.

In WG1 meeting # 10 it will Tdoc R1-00-0092 for the proposal 'frame structure for low chip rate TDD option '("frame structure for the TDD Low chip rate option ") fully discussed. This document gives some background information, explanations and clarifications added.

Conclusion

Based on the meeting and the Agreement is proposed to follow the text below Add section 5.2.1 of TR 25.928.

Changes from TR25.928 beginning 5.2.1.1 Frame structure for the option with lower Chip rate

Both for the option with high chip rate and the option with low chip rate is also Frame length 10 ms. And for the lower option Chiprate is this 10 ms frame in 2 subframes of 5 ms split to quickly update the Power control and beam shaping enable intelligent antenna. The Frame structure for each subframe in the 10 ms Frame section is the same.  

Fig. 1

Frame structure for the low chip rate option

Where n + m + 2 = 7

The frame structure for each subframe is shown in Fig. 1.

• - Tdn: the nth normal down time slot with 864 chips duration;
• - Do: the nth normal upward time slot, 864 chips duration;
• - DwPTS: downward pilot time slot, 96 chips Duration;
• - UpPTS: up-pilot time slot, 160 chips Duration;
• - G: main security period for the TDD Operation, 96 chips duration;

In Fig. 1, the total number of normal traffic time slots for the up and down link is 7, and the length for each normal time slot is 864 chips. Between the downward time slot and the upward time slot, the special period is the switching point for separating the uplink and the downlink. There is only one switch point in each 5 ms subframe for the low chip rate option. The proposed frame structure has taken into account some new technologies, either smart antenna technology (beamforming) or up-synchronization are well supported.

Using the frame structure above the low chip rate TDD option with both work symmetrical as well as asymmetrical mode, by moving the position of the switching point. It should be noted that in the asymmetrical Operating mode at least one normal upward Time slot and a down time slot to traffic can be allocated. The security period G of 96 chips can cover the cell radius of up to about 11 km support the up-synchronization operation, the upward transmission in macro, micro and Pico cells of small cells in cities or large ones Cells in rural areas is advancing.

5.2.1.2 Butt structure for the option with lower Chip rate

According to the frame structure described above, the shock structures for Tdn, Tun, DwPTS and UpPTS are proposed. The shock structure for a normal time slot (Tdn, Tun) is described in Fig. 2.

Fig. 2

Bump structure for normal traffic time slots

In Figure 2, the data symbols on each side of the midamble are 352 chips (with a spreading factor of 16). The TPC bit for power control, the TFCI bit and the additional up-sync bits are included in burst data symbol fields.

The GP field in Fig. 2 for each time slot is used for protection between time slots to avoid the long delay multipath interference. It should be noted that the GP of the last normal traffic burst (Td0) together with the security period in DwPTS is 48 chips long, which is different with another normal security period of 16 chips between time slots. This "super long" safety period can be used to avoid the interference between the last normal down time slot and the down synchronization pilot burst. Otherwise, the disturbances of the last down time slot from the high-performance pilot severely affect traffic; conversely, the down-pilot burst disturbances from the last down-time slot decrease the down-synchronization and cell search performance.

The structure of DwPTS and UpPTS is described in Fig. 3 and Fig. 4.

Fig. 3

Structure for DwPTS

Fig. 4

Structure for UpPTS

In DwPTS and UpPTS the content of the SYNC and SYNC1 fields for the down and up pilot used. The GP fields are used to separate the Downward (upward) pilots from the normal downward (Up) time slot used.

It should be noted that the upward Sync burst (SYNC1) not immediately from an RACH is followed. The order of transmission is as follows: first the UL sync burst from the UE side for timing and Power setting and then the RACH push as one normal impact transmitted with useful signal. This two-step procedure that differs from that of GSM single-phase procedure has a better one Performance than the classic approach used in GSM.  

In this case, the normal traffic jam and the Access burst active in the same time slot, and the Faults are reduced in relation to each other when they are time synchronized.

The proposed framework and with it contiguous butt structure for the option with low chip rate may affect service requirements of the third generation and can Data services up to 2 Mbps in a single 1.6 MHz Provide carrier. And the proposed one Frame structure can cover all environments from macro, micro and support picocells. In the vehicle environment the speed can be more than 120 km / h. In addition, in the proposed framework using some specific properties for the option low chip rate, such as technology the intelligent antenna, the upward Synchronization, beam shaping, etc. well supported become.

Changes from TR25.928 end Lower cell search procedures for the TDD option Chip rate introduction

In 3GPP there are two options for the TDD Mode. These are the high chip rate option (3.84 Mcps) and the option with low chip rate (1.28 Mcps). Although the initial cell search procedure this is carried out in three steps has opted for the low chip rate option their own characteristics and properties,

Cell search procedures

During the initial cell search, this looks for UE after a cell. Then it determines the DwPTS, Subframe and multi-frame synchronization of these Cell and then decodes the content in BCH. This Initial cell search is done in three steps  executed:

Step 1 Search for the DwPTS

During the first step of the initial Cell search procedure the UE uses the SYNC (in DwPTS) to obtain the DwPTS synchronization on a cell. This is usually done with one or more matched filters (or a similar device), which are adapted to the received SYNC, the off the set of gold sequences is selected. This can can be achieved by peaks in the output signal of the adapted filter or the output signals of the adjusted filter can be recognized. The corresponding The maximum peak SYNC is then the SYNC of the strongest cell.

To get a more reliable output on a can get low signal / noise ratio the output signal or the output signals of the matched filter or the matched filter before Decision to accumulate a few subframes.

step 2 Subframe synchronization

During the second step of the initial The cell search procedure receives the UE the BCH to which the DwPTS follows. Because the SYNC and the encryption key of the BCH is individually relevant (that is, as soon as that SYNC is recognized, the BCH encryption key can be determined), the UE can correct the BCH to verify. According to the result of the verification UE go back to the next step or step 1.

step 3 Multi-frame synchronization

During the third step of the initial The UE searches for the head of the cell search procedure Multi-frame and gets the frame number first. And then reads the full broadcast information of the found cell in one or more BCHs.  

Conclusion

This document describes the Cell search procedure for the lower option Chiprate, it is suggested this new feature for the TDD option with low chip rate in the new one Clause 8.3.2 of TR 25.928.

Changes from 25,928 start 8.3 Synchronization and cell search procedures 8.3.1 Upward synchronization 8.3.2. Cell search procedures

During the initial cell search, this looks for UE after a cell. Then it determines the DwPTS, Subframe and multi-frame synchronization of this cell and then decodes the content in BCH. The initial Cell search uses the DwPTS and BCH are in [1] described.

This initial cell search is done in three Steps:

Step 1 DwPTS products

During the first step of the initial Cell search procedure the UE uses the SYNC (in DwPTS) to obtain the DwPTS synchronization on a cell. This is usually done with one or more matched filters (or a similar device), which are adapted to the received SYNC, the off the set of gold sequences is selected. This can can be achieved by peaks in the output signal of the adapted filter or the output signals of the adjusted filter can be recognized. The corresponding The maximum peak SYNC is then the SYNC of the strongest cell.

To get a more reliable output on a can get low signal / noise ratio  the output signal or the output signals of the matched filter or the matched filter before Decision to accumulate a few subframes.

step 2 Subframe synchronization

During the second step of the initial The cell search procedure receives the UE the BCH to which the DwPTS follows. Because the SYNC and the encryption key of the BCH is individually relevant (that is, as soon as that SYNC is recognized, the BCH encryption key can be determined), the UE can correct the BCH to verify. According to the result of the verification UE go back to the next step or step 1.

step 3 Multi-frame synchronization

During the third step of the initial The UE searches for the head of the cell search procedure Multi-frame and gets the frame number first. And then reads the full broadcast information of the found cell in one or more BCHs.

Changes from 25,928 end literature

[1] CWTS WG1: TS C101 V3.0.0, 1999-10, Physical layer - General description
[2] CWTS WG1: TS C102 V3.0.0, 1999-10, Physical Channels and Mapping of Transport Channels onto Physical Channels (physical channels and mapping of transport channels onto physical channels)
[3] CWTS WG1: TS C103 V2.2.0, 1999-10, Multiplexing and Channel Coding (multiplexing and channel coding)
[4] CWTS WG1: TS C104 V3.0.1, 1999-10, Spreading and Modulation (spreading and modulation)
[5] CWTS WG1: TS C105 V3.0.0, 1999-10, Physical layer Procedures

Claims (1)

 Method for signal transmission in a cellular Mobile radio system in which code groups in radio cells (Group 1 ... Group 32) through clear relationships Synchronization sequences (SYNC, SYNC1), Encryption codes and midamble codes defined and the code groups are assigned to the radio cells become.